Distribution Of Mass Transport Deposits Research Articles

Indonesian Throughflow as a preconditioning mechanism for submarine landslides in the Makassar Strait

Abstract The Makassar Strait is an important oceanic gateway, through which the main branch of the Indonesian Throughflow (ITF) transports water from the Pacific to the Indian Ocean. This study identifies a number of moderate (>10 km 3 ) to giant (up to 650 km 3 ) mass transport deposits within the Makassar North Basin Pleistocene–Recent section. The majority of submarine landslides that formed these deposits originated from the Mahakam pro-delta, with the largest skewed to the south. We see clear evidence for ocean-current erosion, lateral transport and contourite deposition across the upper slope. This suggests that the ITF is acting as an along-slope conveyor belt, transporting sediment to the south of the delta, where rapid sedimentation rates and slope oversteepening results in recurring submarine landslides. A frequency for the >100 km 3 failures is tentatively proposed at 0.5 Ma, with smaller events occurring at least every 160 ka. This area is therefore potentially prone to tsunamis generated from these submarine landslides. We identify a disparity between historical fault rupture-triggered tsunamis (located along the Palu-Koro fault zone) and the distribution of mass transport deposits in the subsurface. If these newly identified mass failures are tsunamigenic, they may represent a previously overlooked hazard in the region.

The role of structural growth in controlling the facies and distribution of mass transport deposits in a deep-water salt minibasin

We distinguish two types of mass-transport deposits (MTDs) within a salt-related slope minibasin. The locally-derived MTDs are sourced from growing structures bounding the minibasin, and the more extensive, regional, MTDs are sourced from the shelf of the continental margin, at least 100 km east of the study area. The two types of MTDs have different internal characteristics, distribution within the basin and depositional mechanisms. Using a high-resolution 3D seismic dataset we characterise the internal structures and dimensions of the MTDs, and also quantify the deformation history of the salt structures. Through these analyses we demonstrate that the ‘local’ and ‘regional’ MTDs react in different ways to growth on the structures within, and bounding, the slope minibasin. The regionally derived MTDs are debris flows, with individual deposits up to 300 m thick and covering an area of up to 1300 km2 within the minibasin. Seismic facies analysis suggests they are mostly composed of chaotic material but in some places contain discrete blocks of sediment ranging from 50 m to 250 m in length. In contrast, the more locally derived MTDs are submarine slides consisting of translated material from the flanks of salt structures. Each slide has an up-dip extensional domain with normal faults and a down-dip contractional domain with thrusts and folds. They cover areas between 11 and 28 km2 with frontal and lateral ramps up to 200 m high. Relict topography on the top surface of the MTDs is infilled with younger sediment. Shortening analysis of the intra-slope salt structures within and bounding the minibasin is used as a proxy for the growth rate of the structures. This novel approach of combining shortening with the detailed observations of the local and regional MTDs has allowed us to draw new conclusions on the relationship between structural growth and MTD initiation. Local MTDs either form during periods of high structural growth (10–30 m/ma) or in a period of quiescence (

Mass transport processes in the southern Scotia Sea: Evidence of paleoearthquakes

The southern margin of the Scotia Sea hosts the convergent boundary between the Scotia and Antarctic plates where a number of small basins are situated. Mass transport deposits (MTDs) within two of these small basins, Dove and Scan basins, reveal the importance of seismicity, slope instabilities and depositional processes in their growth patterns. Swath-bathymetry and very high-resolution seismic data show that there are over 200 MTDs in these basins in the last 100ky record. MTD characterizations are determined on the basis of their regional distribution, shape, apparent size and depth. Their sedimentary and tectonic implications are discussed, as well as the evidence of different triggering mechanisms in this region, which is characterized at present by moderate-to-high magnitude, shallow to intermediate earthquakes. MTDs are more abundant in the Dove Basin (with lenticular and wedge shapes), suggesting that this basin was affected by active tectonics to a greater degree than the Scan Basin. This finding is significant in the overall evolutionary context of the Scotia Sea region and Scotia–Antarctic plate geodynamics. Nevertheless, other factors —volcanic activity, vigorous bottom-currents, and/or higher sedimentation rates — must also be considered for the generation of MTDs in the Scan Basin, where a variety of processes generated more diverse MTD morphologies. Paleoseismological estimations of the repeated occurrence of wedge shaped MTDs in contact with fault scarps point to potential sources of large magnitude (Mw ~7.2–7.3) paleoearthquakes in several sites, in agreement with the present high magnitudes of regional seismicity. This study shows MTDs to be appropriate as paleoearthquake indicators in active tectonic settings. The distribution of MTDs in the southern Scotia Sea has important implications for geodynamic and geohazard research. They may prove to be unmistakable stratigraphic markers for future basin analysis.

Analysis on Seismic Characteristics and Triggering Mechanisms of Mass Transport Deposits on the Northern Slope of the South China Sea

AbstractMass transport deposits (MTDs) are one kind of deepwater sedimentary systems driven by the gravity flow action, and play an important role for the deep‐water sedimentation in global continental margins. MTDs are not only one of the most serious deep‐water geo‐hazards, but also have close relationship with the formation and accumulation of marine gas hydrates and deepwater hydrocarbon. Based on the topographic and high resolution seismic data in the hydrocarbon exploration region, we identified the characteristics and distribution of MTDs in the northern slope of the South China Sea. MTDs are characterized by apparent geomorphology and sedimentary structures. In MTDs there are well developed extensional faults in the head and slides and turnover blocks in the middle. Compressive structures and thrust faults are formed in the toe region of MTDs. Several mechanisms can account for development of MTDs. However, Baiyun MTDs were inferred to be dominated by the dissolution of gas hydrate as suggested by the model of gas hydrate reservoirs and numerical modeling using the elastic‐plastic finite element method for MTDs in the Baiyun sag. Six different gas hydrate dissolution models are chosen to calculate the safety factors. We found that the stability of submarine slope decreases with the increasing dissolution of gas hydrate.